1. Field of the Invention
The present invention relates to a turbine or a turbine-generator unit having a tube connected to the turbine downstream for operation with a liquid level which is low or absent downstream of the turbine, and a turbine-generator module comprising a number of turbine-generator units of this type. The invention also relates to the use of a turbine or turbine-generator unit of this type and a method for operating a turbine or turbine-generator unit through which liquid can flow, a method for operating a plant for generating electrical energy, a method for converting a structure for retaining a liquid medium into a device for generating electrical energy, and a method for generating electrical energy at a structure for retaining a liquid medium.
2. Description of the Prior Art
A tube, generally a suction tube, of a turbine or turbine-generator unit in practice always has to open out into the tailwater and must never spray into the open air, since if it does so, particularly in the case of suction tubes with a considerable divergence, the discharge jet can become detached from the suction tube, which reduces the hydraulic efficiency and therefore also the plant efficiency of a turbine-generator unit of this type considerably, to an economically unacceptable level. For this reason, attempts should be made to avoid such a situation in practice.
For design reasons, and in this context in particular, when existing dam structures are being used, it is, however, sometimes not possible to satisfy this condition, since the tailwater level is too low from the outset. Therefore, in a plant of this type, it has hitherto been impossible to install an efficient turbine or turbine-generator unit for generating electrical energy.